Cement gun nozzle



Jan. 2, 1934. J. T. v w 1,941,726

CEMENT GUN NOZZLE Filed Jan. 2, 1930 Patented Jan. 2, 1934 UNITED STATESPATENT OFFICE 3 Claims.

This invention relates to cement gun nozzles and deals with thedeposition of particles of a hydrated concrete mixture upon a surface bythe usual air pressure means. The phenomenon of rebound is well known tothe cement gun industry as a gradation or a series of degrees of reboundranging between necessity at one end and a wholly unnecessary waste ofmaterial at the opposite end. 'In cases where extreme density ofdeposition is the chief aim, the rebound is accepted as the means bywhich the energy of the compressed air is transmitted to the surface tobe condensed. But in cases where the density required is comparable toaverage hand work, rebound becomes an expensive nuisance both withrespect to loss of time and material. This invention, therefore, broadlyspeaking, deals with the control of the amount and kind of rebound whichoccurs when a cementitious mixture is deposited by means of cement gunequipment.

In considering rebound, it is appreciated that two factors are involved.The first factor relates to the nature of the surface on which thedeposit is made to take place, and the second deals with the ballisticproperties of the particles of con- 4 veyed material. Thecharacteristics of the depositing surface bear only an indirect relationto the problem involved in this invention and, consequently, will not bediscussed since the present invention is more concerned with rebound dueto causes more intimately connected with the momentum of air used in thetransporting of the material and with the incident impact of theparticles of material upon the depositing surface.

Rebound, in the sense as used in this invention, is intended to includethe particles deflected from a depositing surface by the force ofincident velocity and also those particles swept from the surface by theblast of released air which is shot directly against the surface withthe material particles. This latter phenomenon may be termed air erosionand is one of the problems sought to be benefited by this invention.

Another aspect of this invention deals with the ballistics of theparticles involved.

As to the ballistics of the'particles of material, it is well understoodthat the incident velocity of the projected particles is derived fromair propulsion. However, as soon as the air has conveyed each particleto the nozzle and has imparted a projecting velocity to the particles,the work of the air is finished and it then becomes a hindrance insteadof a benefit in the further work of depositing. The ideal arrangementwould be a nozzle wherein a complete separation of air from theparticles was effected prior to the particles leaving the nozzle. Underthis arrangement, the particles would proceed on their own path ofprojectionand would travel the remaining distance from the orifice ofthe nozzle to the surface of deposition under their own momentum. Anozzle designed upon this principle is fully described in my copendingapplication, Se-' rial No. 417,648, filed Dec. 31, 1929, and operatesupon the principle of a tromb shaped nozzle whereby the air is deflectedfrom the sand at substantially right angles to the flow of the sand asit leaves the nozzle orifice. It is thus obvious that by separating theair from the material, the disadvantage of sweeping particles, alreadydeposited,v from the depositing surface would be avoided. However, thereremains another method of reducing'rebound and the sweeping action ofthe air or what I term air erosion and that is by reducing the velocityof the air before it leaves the nozzle orifice. Means for this purposeis to be considered as one of the prime objects sought in thisinvention.

For the purpose of reducing air erosion, this invention contemplates apartial absorption of the air velocity at a point prior to the departureof the particles from the nozzle orifice. The principle involved in thisinvention is based upon the theory that the compressed air which isforcing the particles along the path of travel will have performed allof its useful work as soon as the nozzle orifice is reached and thatunless it is deflected or its energy absorbed,'it will continue totravel to the depositing surface and will impart its remaining energy toremoving particles from the surface. In addition to removing particlesit will set up eddy currents or counter currents in direct opposition tothe depositing of material. In order to obviate this condition, I havedevised a nozzle whereby the excess velocity of the air within thenozzle is applied to drawing outside air into the nozzle in a manner topartially absorb the unexpended energy remaining in the air. By thismethod the energy still remaining in the live air after it has deliveredthe particles to the nozzle orifice, is partially absorbed by settinginto motion a volume of static air surrounding the exterior of thenozzle. The direct result is a decrease in the velocity of the sand andair column before leaving the nozzle orifice. This in turn reducesrebound of particles by decreasing the incident velocity and also tendsto decrease air erosion by debilitating the air. A nozzle having theforegoing characteristics will be appreciated as accomplishing the majorpurposes of this invention, namely, to decrease the rebound of particlesby reducing the incident velocity thereof and to decrease air erosion ofdeposited particles by reducing the air velocity before it leaves thenozzle.

An added advantage resides in this arrangement for this reason. It isassumed that the density of deposited product depends largely upon thenozzle pressure. This assumption is based upon practice, and also'uponthe factthat'yarious city and country specifications for Gunitestipulate a minimum nozzle pressure in order to insure a certain densityof product. Therefore, by reason of work performed in the nozzle.proyided by this invention, it is clear that a considerable resistanceis oiiered to the passage of .air therethrough and that, consequently,such a nozzle will maintain a comparatively high nozzle pressure whichconforms to the above requirements in practice.

it .is apparent that :a-com'binati'onof the principle of the "presentinvention may be :made with the principle or :another of inventionsdisclosed :and claimed in any .copending application, Serial No.$17,647, illed Dec. 30, 1929. .In the said "copending application, thevelocity of the partiroles is meduced by mechanical :obstructing means.Evidently, :a combination of the two principles, to wit: the presentinvention, and the foregoing :copending :imren'tion, would :produce .anozzle particularly -su'itable ior depositing cement in quarters whererair eros'icn llS objectionable and where high density of :product is:not required.

In my said :copending application, Serial No. 4117,6228, filed 33cc. 31,1929, I have disclosed :a nozzle involving the ltromb ssh-aped nozzle."Zilhis arrangement, in :conibinati'on with the principles of themresent invention, produces a nozzle tha't greatly reduces *the"velocity of the released air obstruction .in the path of the projected:sand

zpa'rtioles to decrease the velocity of :-said :pa-rtioles; :and

Big. f irshows :an'o'ther combination :of principles :in which theprino'iple of this iinvention is inconporated with "a second principle:of deflecting ithe excess :air ifrom the path of the projectedparticles.

in the drawing herewith, I have :more or less diagrammaticallyiillustrated lmy invention sand haveishown arnozzle diatta'ched to .-awaterlring 2B which in tunn iszmounted :upomaconventionall materialconveying Fhose In all the iforms :n'f nozzles embodied .in ithisinvention, there is in- :curporatedan air massage orra series of airpas- :sages designated :at 11. .The passages i121 :Will'be;appreciatedzaszproviding:communication'fromthe sexterior :of ithenozzle it'o the interior of rsaid mozzle.

ln fthe pperation :of the nozzle embodying the principle oi iaJbsorbingthe excess velocity of the air transporting medium before it leaves thenozzle orifice, which form is illustrated in Fig. 1, the sand particlesare conveyed through the hose C and are hydrated in passing through thewater ring B whereupon they pass outwardly in a sand and air column inthe direction of the arrow 12. As the particles propelled by the aircontinue to pass outwardly through the nozzle A; the air pasages .11beginto operate and serve to communicate the zone of :staticairsurrounding the exterior of the nozzle with the interior of the nozzle.This arrangement is recognized as providing an aspirating means ofdrawing outer .air through the passages 11 into the interior of thenozzle A by means of the excess energy of the 29.211 which hastransported the material to this point and has no further usefulness. Itis readily understood that by thus setting up a mov ment to a volume ofexternal air, a large percentage of the energy of the live air withinthe muzzle is :absorbed. Ellhis .pnimziple of mar- .tielly oalbsorhingthe nelocity or :live air within the nozzle after :it :has performed.its usefulness :by rcans'mg :it to :mone la 'Mclume rof idead air, 113to be considered ;as the heels .of my invention, and operates tomaterially :rednce the viability :of the :sand and :celumn, 1amconsequence -:of which .is to decrease the speed dihe apantiole before:being projected. lBy thus rdeomasing the ,speed of the marfiicles andthe welocity (of the :air, "the rebound of particles due rto velocityand erosion pf ipariiicles mine to 'air is reduced. A nezzlerol thistyperopenateszsezt- .isfactorily 'to deposit ;a large alolume ofipradnct having :an average :clensity. The :chief :benefit of such a:nozzle is the reduction :of zrehonnd clue to incident yelocity andimpact an dihe -;.pz=vrtioles and :a lessening of :air erosion.

,In Fig. .1 have aemlmdied -irltce gpninciples not the presentiinvention the :of an- .other of .:my inventions disclosed :in ssaiidmoncnd- Ling application, ZSmiial .llo. AeIFLGA'Z. it :will foe noted inFig. .3 ithat the :same mozzle 11A zis iutilizefl zin iconsunction witha nonventional water ming Brandzthe usual imaterial conveying hoseiC.Ellhe same zair massages care provided and ithe we- ;locity ef :the.excess air is absorbed in the :same manner. embodied :an :o'bstnuctingcilement 7D arranged :in

:the path .of thesand particles. .pnsposenf this arrangement is itscause a. disturbance .-amongst the particles and thereby appreciablydecrease the velocity :of the particles zthemselves. 'Ihisarrangementobviously increases the rhenefits sought 1130 .be:efiected :by this invention, mamely, :the niinimizingipf rebound of :byade- -creasing the velocity 2 hereof :and ithe reduction of 'air erosion:by absorbing a :certain amount .01 excess .air velocity. A nozzle :ofthis ichamcter ri-s However, in this :arrangement, .=I lnave isparticularly adapted ttoreduee air erosiomand a J todeposit a largevolume of rmaterial wherezdensity-of produc't is notof-.prime2importance.

Fig. 4 illustrates the principle :of the present invention incombination with it-he :prinoiple of another of :my inventions. in theillustration ing the velocity of excess air is identical with the:method disclosed :in the present iil'lXIBlilliDIl.

In combination with this arrangement, zhave illustrated a secondarrangement comprising an adaptation of :a trom'b designated :15 whichis In combination with rthe mile :15,

its

arranged to deflect air separated fromthe column of sand and air byexpansion through passages 16. This principle of deflecting air from thesand column has been fully described and claimed in my copendingapplication, Serial No. 417,648, filed Dec. 31, 1929.

In combining the principle of this invention with the principle of theabove mentioned invention, an intermediate member 1'7 is incorporatedbetween the tromb 15 and a tromb 15' and is shaped in a manner to defineone side of the passages 11 and 16; This type of nozzle may be said tomeet the general requirements of the elimination of air erosion and thereduction of particle speed. A nozzle of this character will findgeneral usefulness in almost all kinds of work.

In the drawings shown, it is to be understood that the principlesinvolved are more or less diagrammatically shown and that this inventionis intended to include all forms of nozzles which embody the principlesdisclosed in the drawing and the specification.

I claim as my invention:

1. In a nozzle for use with cement gun equipment: means for reducing thespeed of the particles projected therethrough, said means includingpassages in said nozzle arranged to communicate the flowing air withinthe nozzle with exterior air surrounding the nozzle; and a particleobstructing element arranged within the orifice of the nozzle. 1

2. A nozzle of the character described comprising: a casing adapted tobe mounted upon a material conveying conduit, said casing embodying anexpanding nozzle having passages communicating the interior of saidnozzle with the exterior air surrounding said nozzle; and a particleobstructing element arranged in the orifice of said nozzle.

3. A nozzle of the character described comprising: a casing adapted tobe mounted on the discharge end of a material conveying conduit, saidcasing forming an expanding nozzle having its inlet end spaced apartfrom the end of the conduit to form an air inlet passage therebetween,and a particle obstructing element centrally disposed in said nozzle.

JOHN T. VAWTER.

